Zoning rules dating back more than 25 years may allow Holcim New Zealand to renew its decades-old plan for a cement works near Oamaru.
Land was bought and zoning granted in the mid-1980s, but the cement giant abandoned its plans because of a lack of confidence in the market.
The company is reappraising the Weston site and expects to seek resource consents for a $200 million plant soon. It now imports cement to supplement domestic production.
The company is also considering a site in Waikato, upgrading its existing plant at Cape Foulwind, near Westport, or importing cement.
The Westport plant, built in the 1950s, is running at capacity.
A decision on which option to pursue will be made by Swiss parent company Holcim Ltd and is not expected until 2008.
If the company builds at Weston, it will gradually scale down its Westport operation.
Strategy and development manager Paul Commons said Westport workers would be offered jobs at Weston.
Over coming months, Holcim will conduct preliminary field work at Weston, Ngapara and Windsor sites and start assessments, such as engineering feasibility, raw material evaluation and ecology.
A Weston plant would have design capacity of 2400 tonnes of clinker a day.
The plant would operate 24 hours a day, seven days a week.
Construction would take about two years.
Cement would be distributed around New Zealand and cement to areas other than the lower half of the South Island would leave Timaru or Port Chalmers by ship.
Holcim has ruled out using Oamaru Harbour because significant dredging would be needed.
The plant would cover 30ha to 40ha, with a main stack 100m high. It would employ about 100 people. Consents will be lodged with the Waitaki District and Otago Regional councils.